Vehicle brake



Feb. 17,1948. l L. R. BucKENDALr-z ET Ax. l 2,435,955

' VEHICLE BRAKE Filed Dec. 22, 1944 `es sheets-sheet 1' ummup Fgb. 17,1948.

.|.. R. BUCKENDALE ET'AL VEHICLE BRAKE Filed Dec. 22, 1944 esheets-sheet 2 LAwRcNcr.

RALPH UCKENDAL:

. SUPER Feb. 1v, 194s.

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A L R. BUCKENDALE Er Al.

VEHICLEV BRAKE V Filed Dec. 22, 1944 6 Sheets-Sheet 3 LAWRENCE R.BUCKENDALE RALPH K. SUPER Feb. 1 7, 19.48. `l.. R. BUCKENDALE Er A|2,435,955

VEHICLE BRAKE Filed Dec. 22, 1944 6 Sheets-Sheet 4 LAWRENCE R.vBUCKENDALE RALPH IK. SUPER Feb. 17, 1948. R. BuKl-:NDALE ETAL 2,435,955

vnnIcLE mmm Filed nec'. 22, 1944 s sheets-sheet 5 LAWRENCE R. BucnENoALERALPH K. SUPER Pi 17; 194MB.

L. R. BUCKENDALE ETA. 2,435,955

vEnIcLE BRAKE Filed nu. 22, 1944 6 sneet$-sheet e l i gw'uvwtou.

LAWRENCE R. BUCKENDAL:

RALPH K. SUPER' Patented Feb. 17, 1948 VEHICLE BRAKE Lawrence R.Buckendale and RalphK. Super,

Detroit, Mich., asslgnors to The Tlmken-Detroit Axle Company, Detroit,Mieli., a corporation of Ohio Application December 22, 1944, Serial No.569,392

14Claiml. (Cl. 18S-78) This invention relates to improvements in vehiclebrakes and has particular reference to an improved brake oi' thecharacter referred to in the art as a "dual primary" .brake anddisclosed in United States Letters Patent No. 2,337,069 and No.2,337,070. a While dual primary brakes have proved to be highlysatisfactory in operation and the operative principles have beensuccessfully demonstrated, certain practical problems have arisen inconnection with the production and operation of such brakes which it isamong the objects of the present invention to solve.

The more important problems encountered in the construction andoperation of brakes of the character indicated involve the provision ofthe best means of supporting the brake shoes, actuating levers, and shoeexpanding means, and the provision of brake shoe adjusting means havinga range of adjustment such that the entire effective thickness of 'evena thick lining can be used up without producing uneven Wear or l getherwith means automatically maintaining a exposing any of the lining rivetsor any portion of the shoe surface to contact with the brake drum.

They also involve the'provision of an economical brake mechanismcompactly arranged to fit into the limited space available on a heavyduty vehicle,'with parts readily accessible for adjustment and repairand of a simplified construction with a minimum number of parts.

Problems have also arisen from the circumF stance that some vehicles towhich the brakes are applied are equipped with hydraulic brake systemswhile others use pneumatic brake actuators or boosters energized bycompressed air or by engine manifold vacuum so that the brakes must beadapted for either method of operation.

Some diiilculty has also been encountered in preventing overheating ofthe brakes on certain types of heavy duty vehicles, particularly in thecase of brakes associated with dual Wheels when Ait is necessary toenclose a large portion of the heat radiating area of the brake drum.

With these and other considerations in view, it is an important objectof the invention to provide an improved vehicle brake mechanismparticularly adapted for economical quantity production.

A further object resides in the provision of an improved vehicle brakemechanism of the character indicated having a range of adjustabillty for1lning wear sufficient to use up the available thickness of thick heavyduty linings, to-

substantially concentric relation between thc brake lining and brakedrum with a uniform application of braking pressure throughout thesurface area of the lining.

A still further object resides in the provision of an improved brakemechanism of the character indicated having a compact arrangement sothat brakes of adequate size and capacity may be fitted into the limitedspaces available on heavy duty vehicles.'

It is another object of the invention to provide novel equalizingcoupling means between the brake levers and the actuating means thereforto insure the equal transmission of braking forces through said leversto the respective brake shoes.

.An additionall object residesy in the provision of an improved brakemechanism of the char-- acter indicated which may be readily convertedfrom hydraulic to pneumatic operation or vice versa.

Another object resides in the provision of an improved brake mechanismof the character in-4 'merals are used to designate similar partsthroughout, there is illustrated a suitable mechanical embodiment forthe purpose of disclosing the invention. The drawings, however, are forpurposes of illustration only and are not t0 be taken in a limiting orrestrictive sense as it will be apparent to those skilled in the artthat various changes in the illustrated embodiment may be resorted towithout in any way exceeding the scope of the invention.

In the drawings:

Figure i is an elevational view of the improved brake mechanism with thebrake drum removed and the dust shield and shoe actuating lever omittedfrom the right hand half;

Figure 2 is a fragmentary sectional view on an enlarged scale on theline 2-.2 of Figure 1 showing one ofthe brake shoe supporting andadjusting devices;

Figure 3 is a fragmentary sectional view on an enlarged scale on theline 3-3 of Figure 1 showing one of the shoe supporting anchor pins;

Figure 4 is a fragmentary sectional viewon the line I-l oi' Figure 1showing a transverse section through the brake shoe and actuating lever;

Figure 5 is a fragmentary sectional view on the line 5--5 of Figure 1showing the hydraulic Figure 8 is an elevational view of a. fragmen-`tary portion of the pneumatic brake actuating mechanism;

Figures 9 and 10 are diagrammatic views illustrating the relativedisplacement between each shoe and lever during the entire wearadjustmentV range, Figure 10 illustrating the inclined saddle bar faceof the invention;

l. Figure 11 is a detail sectional view taken substantially on the lineII--Il of Figure 7, and

Figure 12 is a similar view of a, modied construction.

With continued reference to the drawings and particularly to Figures1.to 6 inclusive, the numeral i generally indicates the brake spider orfoundation member which supports the movable part of the brakemechanism. This foundation member is preferably a steel forging and isrigidly secured to the axle housing by means of bolts or rivets l2, asshown in Figures 2 and 3, passing through suitable apertured bosses inthe foundation member and through registering apertures in a brakeadapter ange I4 welded or otherwise permanently secured on the axlehousing I5, or may itself be directly permanently secured on the axlehousing, as is clearly illustrated in Figure 6, by suitable means suchas the welds I6.

This foundation member I8 is provided with angularly spaced aperturedbosses or lugs, as indicated at I8, 20, 22, and 2,4 in Figure 1, whichreceive and support corresponding anchor pins 26, 28, 3U, and 32.

Two brakev actuating levers 34 and 35, one of which is generallyindicated at 34 in Figure 1, are pivoted at their lower ends on theanchor pins 28 and 26 respectively. Brake shoes, as indicated at 36 and38, are operatively associated with the levers and engaged by abutmentmembers 40. 42, 44, and 46 pivotally supported on the respective anchorpins.

Each lever member comprises a pair of similar spaced parallel plates asindicated at 34a and 34h in Figure 4. A saddle bar, as indicated at 48,is disposed between the plates at approximately the mid-length of theirinner edge portions and buttwelded to both of the plates. A spacer, asindicated at 50 in Figure 1 which may conveniently comprise a sleeve, isinserted between registering apertures and a rivet or pin member extendsthrough said apertures and sleeve and is expanded at its ends.

The brake shoes are substantially identical and the shoe 38, selectedfor detailed description, comprises an arcuate wide flanged portion 62and an integral web portion 54 which extends between the plates of thecorresponding shoe actuating lever and is provided at its end withplanar abutment surfaces 63 and 55 which respectively engage thecorresponding anchor pins supported abutment kmembers 42 and 44, and atits mid-length portion with an arcuate recess, as indicated at 56. Theange 62 carries brake lining, as indicated at 58, which may be eitherriveted or cemented to the ilange and which in the case of the thickerlinings, may be divided into two or more pieces in order to relieve therivets or cement from the strain incident to the tendency of the thicklining to pull away from the brake shoe. j

A pressure block 68 of-generally semi-circular plan form is disposedbetween the saddle bar 48 and the recessed portion 56 of the shoe. weband is held in compression between'the saddle bar andthe shoe web by a,compression spring 62 iwhich is disposed in registering apertures in theIport the lower ends 'of the shoe actuating levers are similar inconstruction and the anchor pin 26 has been selected fox;I detaileddescription and is particularly illustrated in Figure 2, Pin 26 is inthe form of a bolt having at one end a, non circular portion 64 adjacentwhich is a screw threaded portion 66, a cylindrical pilot portion 68dimensioned to closely and rotatably llt the cylindrical pin receivingaperture in foundation member l0, an annular concentric ange which bearsagainst the side of the foundation member opposite a nut 12 screwthreaded on the threaded portion 66, a cylindrical eccentric portion 14and a grooved end portion 16 at its other end coaxial with the parts 64and 68. As is fully shown-in Figure 2 the eccentric portion 14 extendsthrough both side plates 35a and 35h of the lever 35 'and through thebrake shoe abutment 40 which is disposed between the side plates of thelever, the lever and abutment member being secured on the pin by one endof a connecting member 11 between said pin and the opposite pin 28 and aresilient key 18 engaged in the groove of the end 16 of pin 26.

With the arrangement illustrated, the associated shoe and levercomponents may be adjusted for lining wear by rotating the anchor pin26. To accomplish this, nut 12 is loosened, the pin is turned by thesquared or non-circular end por tion 64 to the proper adjusted positionand the nut is then tightened against the lock washer which holds itagainst accidental displacement. An alternate twist lock washer 82 maybe disposed between iiange 10 and the adjacent surface of foundationmember l0 to hold the pin against rotation away from its adjustedposition. Shoe 38 and lever 34 are similarly adjusted by rotating pin28.

It will be noted that by means of the above construction a simultaneousand equal adjustment of the shoe and its actuating lever, at their loweranchored ends, is obtained by the operation of a single cam oreccentric. As the abutment 40 is moved upwardly and to the right (seeFigure 1) to reduce the distance between said abutment and the upper.abutment 46 and move the brake shoe toward the drum, the lever plates35a and 35h-are similarly adjusted to lengthen the mechanical connectionbetween said plates and the brake actuating unit to be presentlydescribed.

Figure 9 illustrates the changes in relative positions of each lever andits associated shoe during the wear adjustment range. Suppose that withnew lining on the brake shoe and cam 14 in the dash-line position, theplanar face 49 of saddle bar 48 is disposed normal to the resultant R ofthe brake applying forces transmitted through pressure block 89, asillustrated in dash lines in Figure 9, this being the condition forpivot and having only the same movement as the abutments, cannot exactlyfollow this radial movement of the shoe, there is relative angularmovement between lever 94 and shoe 38 so that face 49 tilts with respectto its original normal position. i

In order for pressure block 90 and face 49 to maintain full surfaceengagement after such adjustment, the pressure block, accordingly, rocksabout its axis and these parts assume the longshort dash line positionsof Figure v9.V I have found that face 49 may rock six degrees (6) ormore during the range of wear adjustment. A

considerable component of brake applying force is lost in this relationof the parts.

According to one phase of the invention, I halve the degree of departureof face 49 from the normal by arranging face 49, with new lining, at anangle to the normal equal to half the calculated total angulardisplacement of face 49 during adjustment so that when the lining ishalf worn and properly adjusted the face 49 is at its optimum normalposition and at no time is more than half the total angulardisplacement, here three degrees (3). from the normal.

This new arrangement is illustrated in Figure which illustrates in shortdash lines, full lines,

and long and short dash lines the relative position of cam 14 and face49 during initial new lining, half worn lining and fully worn liningconditions. This arrangement is more efiicient than that of Figure 9.

By reason of the small angle of the face 49 of bar 48, the brakeapplying thrust forces will be transmitted through the lever to thebrake shoe in all adjusted positions of said shoe and lever in lineswhich are substantially normal to the connecting line between the axesof the rotatable abutments. In this manner concentricity of the brakelining with the wall of the brake drum is maintained with thesimultaneous application and distribution of braking pressure throughoutIthe surface area of the lining to the surface oi' the drum wall.

The brake maybe actuated by various shoe expanding means, a hydraulicdevice being illus-I trated in Figures 1 and 5, and a pneumaticallyactuated shoe expanding device in Figures 6, 7, 8, 11 and 12, Forsupporting the hydraulic shoe expanding mechanism, a bracket 99 isprovided having apertures adjacent its -ends and an apertured boss 90 atapproximately the center thereof. Anchor pins and 32 pass through Vtheend apertures and rigidly secure bracket 89 to foundation member I0.

A suitable wheel brake cylinder, generally indicated at 94, is providedon one side thereof and at substantially its mid-length position with anapertured boss 96 which is received in the aperture of the boss 90. Theapertured boss 99 is provided with a terminal portion 98 which con-.nects a suitable hydraulic fluid conduit with the interior of thecylinder and the cylinder is secured to the bracket I9 by suitable meanssuch as cap screws, one of which is indicated at |09. Internally of thecylinder is a, pair of opposed pistons, one of which is indicated at |82in Figure 1, connected by suitable links, as indicated at |04, with thespacers l0 surrounding the pins or rivets at the upper ends of the shoeactuating levers.

With this construction when hydraulic iluid under pressure is admittedto the interior of the cylinder 94 the pistons'are forced apart movingthe upper ends of the shoe actuating levers outwardly to. bring the shoelinings into contact with the inner surface of the brake drum. The upperends of the levers are moved inwardly to bring the shoes out of contactwith the drum by suitable means such as the simple tension spring |09secured at its ends topins passing through the upper end portions of theshoe actuating levers. Preferably the cylinder 94 is protected from thelliet of the brake drum by a suitable metal shield 'I'he pins 98 and 92are similar and pin 32 is particularly illustrated in Figure 3. Pin 32may comprise a cylindrical bolt member having intermediate its length aflange or shoulder 33, a threaded end portion 31 upon which is threadeda retaining nut 39 which clamps the end of bracket 89 to lug portion 24of the foundation member At its outer end the bolt may be provided withan annular groove receiving a resilient key which retains the end ofconnecting member 11' in place against the outer surface of the brakeshoe lever 35.

The apertures in the lower ends of the brake levers are circular andclosely fit the eccentric portion 14 of the pins 2 9 and 28 while theapertures 31 in the upper end portions of the brake levers through whichthe pins 39 and 32 project' are elongated to provide freedom of movementof the upper portions of the brake levers relative to the upper anchorpins.

Connecting members 11 and 11' between lower and upper anchor pinsrespectively serve as braces in the assembly.

Referring now to Figure 6 wherein the foundation member or spider i9 iswelded directly onto the exterior of the axle housing I5, it will beobserved that this support member is located intermediate the width of`the brake shoes and that theanchor pins and all other parts of thebrake mechanism are contained between the planes of the opposite sideedges of the brake shoes. arrangement wherein substantially all of thespace allotted to the brake may be taken up by the width of the brakeshoes and brake drum without the necessity of providing space beyond theshoes and drum for the support member and other components of the brakemechanism. Also,

by providing for the maximum rshoe and drum 'width the diameter of thedrum can be held at a i end of the axle housing l5, spacedyanti-friction roller bearings |24 and |29 being disposed between thehub and the wheel bearing sleeve. An axle-shaft |28 extends through thehousing and This provides a compact and convenient the wheel bearingsleeve and is connected to the outer end of the hub by suitable meanssuch as the stud bolts |30. A suitable oil seal |52 is disposed betweenthe axle housing and the hub to prevent hub lubricant from leaking intothe brake mechanism and a brake drum, generally indicated at |84, issecured to the hub by suitable means such as the lug bolts |38 whichalso serve to secure the tire rims to the hubs. An oil baille |38 issecured tothe hub by the lug bolts |08 and has a flange portionoverlying the seal |82 to direct any lubricant leaking past the sealaway from the brake mechanism.

If desired a dust shield (not illustrated) may' be secured to the axlehousing I at the opened end of the drum to exclude dirt and water fromthe brake mechanism. It has been found however that, particularly in thecase of heavy duty brakes, with the dust shield omitted suillcient dirtand water does not enter the brake mechanism to seriously affect theoperation of the brake. Omission of the dust shield permits the freeentry of cooling air into the brake mechanism and suitable apertures, asindicated at |40, maybe provided in the brake drum to permit the air toflow into the brake mechanism at one side thereof, through the brakemechanism and out of the opposite side. These apertures also provide acertain amount of forced circulation when the drums are rotating and areof particular advantage when the drums are enclosed in the inner tirerims as is the case in the construction illustrated in Figure 6. Theouter edge of the foundation member i0 is spaced away from the innersurface .of the brake drum in order to provide ample space between thismember and the brake drum for the flow of cooling air through the brakemechanism.

As explained above, the improved brake mechanism may be convenientlyactuated by either hydraulic or pneumatic means and a suitable pneumaticoperating mechanism is shown in Fignres 6, 7 and 8. In the arrangementillustrated, a torque shaft |42 is mounted on the axle housingby'suitabie brackets with its axis parallel to the axis of the axle. Atits inner end the torque shaft is provided with a lever |44 the free endof which is connected by suitable link mechanism |48 to the piston rodof a pneumatic actuator, generally indicated at |48. The actuator |48may be of any suitable or desired construction and may be operatedeither by compressed air or by engine intake manifold vacuum in someconven tional or desired manner. Operation of the actuator |48 actingthrough the arm '|44 acts to rotate or oscillate the shaft |42 about itslongitudinal axis in its support on the axle housing.

At its outer end the shaft |42 is journalled in a bearing cage |50secured to a bracket 89a which is similar to bracket 89 but differs fromit in detail. Bracket 85a. is secured to foundation member I0 bycorresponding anchor pins as described above. Cage |50 is equipped withan anti-friction bearing such as the needle bearing |52. The

y inner end of the shaft |42 is provided with a concentric enlargement,as indicated at |54, having a diametricai tongue |55 thereon,illustrated in detail in Figure l1. A generally cylindrical head |58 isretained on the end of. the shaft by means of a stud |60 screw threadedinto the end of the shaft and extending through the head. The head isprovided with a groove which receives the tongue |55 and with anenlarged aperture through which the stud |50 passes. A nut |52 is screwthreaded onto the outer end of the 8 stud and compresses a coil spring|54 against the outer end of the head so that the head is maintainedsecurely against the outer end of the shaft but has a limited freedom ofmovement longitudinally of the tongue |58 for a purpose to be presentlydescribed. The side portions of the head |58 are cut away between thetwo end portions thereof and pins, as indicated at |55 and |88, extendone through each cutaway portion and are mounted at their ends in theend portions of the head. These pins are substantially diametrlcallyopposed and are arranged on opposite sides of the stud |80. A pivotedtoggle link |10, Figure 7, extends outwardly from the pin |85 and ispivotally connected at its outer end to the corresponding end of brakeshoe actuating lever 35. Similarly, a pivoted toggle link |12 extendsoutwardly from the pin |50 to a pivotal connection with thecorresponding end oi' the other brake shoe actuating lever, notillustrated.

With this arrangement. clockwise rotation of shaft |42 will rotate thehead |58 with the pins |66 and |68 which will move the toggle links |10and |12 outwardly simultaneously, moving the corresponding ends of theshoe actuating levers to, bring-the shoes into contact with the brakedrum. If the initial clearance between the shoes and the drum is notidentical for both shoes the torque transmitting connection comprisingthe tongue |56 and the corresponding groove in the head member |58 willpermit the head member to slide on tongue |55 and find its own centermodified, and in' some respects preferable, ar-

rangement for converting the rotational movements of shaft |42 intobrake applying and releasing movements of the shoe actuating levers.

In this arrangement stud |60 and compression spring |64 are omitted, anda tongue |55 of T section or dovetail shape is provided 0n the shaftenlargement slidably received in a similarly shaped groove or guidewayin the head. The shape of the tongue and groove construction retains thehead on the shaft while permitting sliding equalizing movement of thehead transversely of the shaft along the tongue.

Itis also to be noted in Figure 7 that the brake shoes are disposed oneat each side of a horizontal line passing through the geometrical centerof the brake mechanism rather than upon opposite sides of a Verticalline passing through said center as is the case in the arrangement shownin Figure 1. It has been found that the shoes will operate with equalefficiency in either arrangement and the arrangement symmetrical of thehorizontal line permits the actuating mechanism to be disposed to thefront or rear of the axle where it does not interfere with the clearancebetween the axle and the chassis of the vehicle and does not interferein any way with the vehicle spring suspension.

In adapting the improved brake mechanism for either-hydraulic orpneumatic operation it is necessary to incorporate the correct bracket89 or 89a, the remainder of the brake mechanism being the same foreither method of operation. This not only provides for easy conversionof the brake mechanism from one manner of operation to the other butgreatly simplifies the manufacturing and servicing of the brakes sinceall of the brake parts except the special brackets are the same for bothactuating means,

The invention may be embodied in other spe-v cific forms withoutdeparting from the spirit or essential characteristics thereof. Thelpresent embodiments are therefore to be rconsidered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the.foregoingdescription and all changes which come Within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. Brake mechanism comprising an anchor pin mounted for adjustment byrotation about its axis, a cylindrical eccentric on said pin androtatable therewith, a brake shoe abutmentmember pivotally mounted onsaid eccentric, a lever pivotally mounted on said eccentric, and a brakeshoe having an abutment surface slidingly engaged with said abutmentmember and having a rockable and sliding motion transmitting connectionwith said lever, whereby said brake shoe and lever are simultaneouslyadjusted upon rotation of said pin about its axis.

2. In a brake mechanism; a relatively fixed foundation member-having aplurality of angularly spaced apertured bosses; two pairs of anchor pinsmounted in four of said bosses; a brake shoe abutment on each anchorpin; a pair of brake shoes supported by said abutments for movementradially of said mechanism; a pair of brake actuating levers eachpivoted at one end on va respective anchor pin; and a shoe expandingdevice supported by said foundation member between adjacent ends of saidlevers and operatively associated with said lever ends.

3. The brake mechanism as defined in claim 2 wherein the anchor pins onwhich said levers are pivoted are provided with eccentric cam portionsextending through said lever ends and the corresponding brake shoeabutments and are rotatably adjustable tov adjust said levers and brakeshoes for brake lining wear.

4. The brake mechanism as defined in claim 2 wherein said shoe expandingdevice comprises a rotatable shaft journalled on said foundation member;a head on the end of said shaft; a pair of pins carried by said headspaced from the axis of rotation of said shaft; and a respective linkconnecting each pin with a corresponding shoe actuating lever end.-

5. The brake mechanism as defined in claim 2 wherein said shoe expandingdevice comprises'a rotatable shaft journ'alled on said foundationmember; a head on the end of `said shaft: a pair of pins carried by saidhead spaced from the axis of rotation of said shaft; and a respectivelink connecting each pin with a corresponding shoe actuating lever end;kand a torque transmitting connection between said shaft and said headproviding freedom of movement of said head transversely of said shaft toequalize the pressures exerted on said lever ends by said links.

6. The brake mechanism as defined in claim 2 wherein saidshoe expandingdevice comprises a bearing cage secured to said foundation member; ashaft journalled in said bearing cage; a head on said shaft carrying apair of pins spaced from the axis of said shaft and angularly spacedfrom each other; a toggle link connecting each pin with a shoe actuatinglever end; and a slidable torque transmitting connection between saidshaft ani .said head operative to equalize the pressure cxerted on saidlever ends by providing freedom of each side of aline passing throughthe center of said foundation member with the pins of each pairsubstantially equally spaced from a line perpendicular to said :Erstmentioned line at said center; e, pair of lever members each pivoted atone end on an anchor pin of the corresponding pair of anchor pins andeach comprising a pair of spaced parallel plates and a Saddle barjoining said plates along the inner edges thereof intermediate thelength of said lever; a pair of brake shoes each having a liningsupporting flange portion and a web portion received between the platesof a corresponding lever and provided with an arcuate recess; agenerally semcircular shaped pressure block received in each recess andbearing against the associated saddle bar; shoe abutments mounted one oneach anchor pin and supporting said shoes in operative position; andresilient means acting between the lever and shoe' of .each shoe andlever combination to maintain:v the corresponding pressure block undercomprese sion between the shoe web and the saddle bar; each saddle barhaving its pressure plate contact-j' ing surface inclined to a linejoining the anchor pins associated with the corresponding lever.

8. A brake shoe actuating lever comprising a pair of spaced parallelplate members having registering apertures in the opposite end4 portionsthereof; and a saddle bar ioiningsaid plate members along the inneredges thereof intermediate the length of said lever, said saddle barhaving the operative surface thereof inclined relative `to aline'joining the center lines of said apertures- 9. Brake mechanismcomprising a brake shoe actuating lever pivotally supported at one o'fits ends; an abutment member adjacent each end of the lever; a brakeshoe having opposite end portions in contact with the respectiveabutment members; means operatively associating 'said brake shoe andsaid lever for angular movement about an axis transverse to the leverand constituting the sole means for transmitting the brake applyingmovement of said lever to said brake shoe; and means for variablyadjusting the spaced apart relation of said abutment members tocompensate for brake wear comprising a rotatably adjustable anchor pinfor the pivoted end of said lever having a single eccentric portioncoacting with said lever and the corresponding abutment member tosimultaneously and equally adjust the angular positions of said leverand abutment member with respect to the pivot axis of the lever 10. Incombination with a mounting member adapted to be secured upon an axlehousing;

diametrically opposed brake lever and shoe assemblies on said member,anchor pins for corresponding ends of the brake levers rotatably mountedin said member and each having means coacting with the associated leverand-shoe assembly to' spect to said pins, and means for selectively andinterchangeably mounting different types of brake actuating units uponsaid additional anchor pins for operative connection with said levers.

l1. In a brake mechanism, a brake lever pivananas oted at one end andconnected to an actuator at its other end, a brake shoe supportedbetween pivoted abutments at circumierentially spaced portions andhaving a rocking sliding motion transmitting coupling with said leverthrough a pressure block having an arcuate face engaged with a recess insaid shoe and a planar face engaged with a planar face on said lever,and means for adjusting said brake shoe for compensating for liningwear, the planar face of said lever being arranged at an initial smallangle with 'respect to normal to the resultant of brake applying forcestransmitted through said pressure block and adapted to pass throughparallelism with said normal during the range of wear adjustment of saidbrake shoe.

12. A vehicle brake mechanism comprising a relatively xed foundationmember, four angularly spaced anchor pins mounted on said foundationmember, brake levers pivotally mounted adjacent one end on two adjacentanchor pins, said levers being provided at their other ends withelongated openings through which the other two of said anchor pins pass,means on said other two pins preventing movement of said brake leversaxially of said pins, a bracket secured to said foundation member bysaid other two an chor pins, and a brake lever expanding device mountedon said bracket and operatively connected to said levers.

13. In a brake mechanism having an annular brake drum of substantialwidth journalled on an axlehousing and surrounding a portion of thehousing, a foundation member fixed on said housing portion at a locationintermediate the width of and parallel to but spaced from a planebisecting the Width of said drum, brake shoes and shoe actuating leverssupported on said foundation member, said levers being connnected tosaid shoes by means lying in said bisecting plane 12 whereby the line otthrust ot vforces exerted by said levers on said shoes lie in saidbisecting plane, and a shoe expanding device supported on saidfoundation member and operatively associated with said levers.

` 14. In a vehicle brake mechanism.' a pair or brake shoe actuatinglevers pivoted at adjacent ends and having their ends oppositev thepivots connected by .an expanding device, and a brake shoe rockably andslidably connected to each lever, said expanding device comprising ashaft journaled on an axis substantially parallel to said pivots, a headon said shaft, a pair of links each pivotally connected to said headeccentrically of the axis o! rotation of said shaft and pivotallyconnected to the respective levers at said ends opposite the leverpivots, and a torque transmitting connection between said shaft and saidhead providing freedom of movement of said head transversely of saidshaft to equalize the pressures exerted on said lever ends by saidlinks.

LAWRENCE R. BUCKENDALE. RALPH K. SUPER.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 22,586 Spiller et al. Jan. 2,1945 Re. 22,604 Alden et al Feb. 30,y 1945 1,812,551 Poulet June 30,1931 1,971,861 LaBrie Aug. 28, 1934 2,212,523 Hawley Aug. 27. 19402,247,374 Hawley July 1, 1941 870,666 Cookingham Nov. 12, 1907 1,980,512White Nov. 13. 1934 1,847,319 Wentworth Mar. 1, 1932

